Re: WalSndWakeup() and synchronous_commit=off

On 11 May 2012 19:45, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Andres Freund <andres(at)2ndquadrant(dot)com> writes:
>> Its the only place though which knows whether its actually sensible to wakeup
>> the walsender. We could make it return whether it wrote anything and do the
>> wakeup at the callers. I count 4 different callsites which would be an
>> annoying duplication but I don't really see anything better right now.
>
> Another point here is that XLogWrite is not only normally called with
> the lock held, but inside a critical section.  I see no reason to take
> the risk of doing signal sending inside critical sections.
>
> BTW, a depressingly large fraction of the existing calls to WalSndWakeup
> are also inside critical sections, generally for no good reason that I
> can see.  For example, in EndPrepare(), why was the call placed where
> it is and not down beside SyncRepWaitForLSN?

I think because nobody thought of that.

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 Simon Riggs                   http://www.2ndQuadrant.com/
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